Square has been selling the latest version of its
tiny credit card reader since last fall, and just rolled out
an iPhone
app called Card Case that could replace the loyalty and
discount cards that merchants use, and an iPad app that could
replace the cash register.

Founder Jack Dorsey recently tweeted that Square is processing
more than $3 million in transactions per day. A picture of
the company's dashboard back in April revealed it was pulling in
about
$60,000 in revenue per day on $2 million in transactions, so
that means it's probably close to $100,000 per day.